So being new to OpenCV, I’m trying to detect a part of the image ( the thick line between the "PSSU" and "356750 / 22G1" characters ) and then subtract it from the original image. I want to have a clean final image that I can then put through OCR.
I’ve managed to detect the line ( red highlights ).
The code for line detection is shown below :
import cv2 import numpy as np # Reading the required image in # which operations are to be done. # Make sure that the image is in the same # directory in which this python program is img = cv2.imread('c:\\ml\\test.jpg') # Convert the img to grayscale gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) # Apply edge detection method on the image edges = cv2.Canny(gray, 50, 150, apertureSize=3) # This returns an array of r and theta values # 4th value ( 400 ) is threshold of how thick the line is thats to be detected. Higher value = thicker line to be detected. lines = cv2.HoughLines(edges, 1, np.pi/180, 400) # The below for loop runs till r and theta values # are in the range of the 2d array for r_theta in lines: arr = np.array(r_theta, dtype=np.float64) r, theta = arr # Stores the value of cos(theta) in a a = np.cos(theta) # Stores the value of sin(theta) in b b = np.sin(theta) # x0 stores the value rcos(theta) x0 = a*r # y0 stores the value rsin(theta) y0 = b*r # x1 stores the rounded off value of (rcos(theta)-1000sin(theta)) x1 = int(x0 + 1000*(-b)) # y1 stores the rounded off value of (rsin(theta)+1000cos(theta)) y1 = int(y0 + 1000*(a)) # x2 stores the rounded off value of (rcos(theta)+1000sin(theta)) x2 = int(x0 - 1000*(-b)) # y2 stores the rounded off value of (rsin(theta)-1000cos(theta)) y2 = int(y0 - 1000*(a)) # cv2.line draws a line in img from the point(x1,y1) to (x2,y2). # (0,0,255) denotes the colour of the line to be # drawn. In this case, it is red. cv2.line(img, (x1, y1), (x2, y2), (0, 0, 255), 2) # All the changes made in the input image are finally # written on a new image houghlines.jpg cv2.imwrite('linesDetected.jpg', img)
So how do I now subtract the line ( red highlights ) from the original image?
(x1, y1) and
(x2, y2) you can slice the image in two parts like:
img_left = img[0:x1, 0:y1] img_right = img[0:x2, 0:y2]
And then join them back:
final_img = np.concatenate((img_left, img_right), axis=1)